Ring Flash options for Sony Alpha a6000

Hello, I´m new in this forum but I searched a lot before asking these questions.

Sony has their macro flashes, but I think that their Twin flash is expensive and the ring flash is just a ring light, not a proper flash. And I read that the Ring Light is not too strong.

I´m trying to find out other options, because I´m afraid to buy an unit that doesn-t work or could damage the hot shoe (high voltage trigger).

From my search in this forum I learned that the multi interface shoe in my camera can accept "regular" flashes, but can only trigger then. It can´t sync (TTL). I would have to use manual mode. It´s ok for me, but I´m afraid to buy a flash that could damage my camera because I can´t find information about their voltage.

I found out that the Sigma EM 140DG Macro has a sony/minolta shoe and offer TTL. I thought I could use a Sony adaptor (multi interface to iISO/sony-minolta) and still got the TTL function. But again I don´t know and can´t find any details about it´s voltage.

I searched a lot and found that most sony cameras accept up to 5,5V on their shoes, so I´m assuming this is fine/safe also for my camera.

Anyone could help me or suggest a solution?

Thanks!

PS: 1) sorry for my english, I´m from brazil and I could not get any help here. Sony doesn´t even has the a6000 here:-O

2) I will use the flash for dental photography, so usually the ring flash has a more versatile use than the twin flash.